Questions of Week_23 Feb

Do we say Carbon Fixation or Cabon Dioxide Fixation?

Both terms have been used by different texts so there is no issue with either. But usually we would say carbon dioxide is fixed into the cycle so to avoid confusion and to adhere to notes, I would advise to use carbon dioxide fixation.

Can cyclic photophosphorylation run by itself?

*amended*
yes. Cyclic photophosphorylation will run when there is not sufficient ATP in the stroma (ATP/NADPH ratio) (switch from non-cyclic to cyclic).
Note: there will be more than one electron involved in the cyclic pathway, when we considered those coming from PSII as well. Thus technically, we do not consider p700 as the electron donor although (and unless) in an isolated system where it will provide that first one electron for cyclic photophosphorylation






Why do we call the TCA cycle light-independent reaction? Can it occur without light?

Light-independent reaction is so called because it can occur in darkness but only in a while. The reaction still requires products i.e. ATP and NADPH from the light dependent reaction. When those are exhausted, the Calvin cycle cannot proceed.
So when you switched from light to darkness, there will be a transition period of time when Calvin cycle continued until it stops.